The first is the least known today. It was elaborated by medieval historians and received its final form in the 16th century from George Buchanan, humanist and the finest Latin poet of the age — the greatest since ­Virgil, according to his contemporaries. It was devised in opposition to Geoffrey of ­Monmouth’s Anglo-Welsh myth of Brutus or Brut, the Trojan prince and father of the British people. Since this version of history gave Brut and his successors sovereignty over the whole island of Britain, it became necessary for ­patriotic Scots to find a means of trumping it. They did so by producing a Greek prince called Gaythelos (Gaedil Glas, “the name ­indicating he was a Gael”), who travelled to Egypt where he married Scota, a pharaoh’s daughter, and then, by way of sojourns in Spain and Ireland, arrived in Scotland in 333BC.

This was very satisfactory because it enabled the Scots, who were only one of the peoples of Scotland, alongside Picts and Britons, and indeed comparative­ly recent arr­ivals from Ireland, to take poss­ession of the whole history of Scotland. Lists of kings (all ­imaginary, dating from Fergus, son of Feuchar) were produced as evidence of this antiquity. In this way, the Scots established their right to independence, disproving the claims of English kings, notably Edward I, to sovereignty over Scotland.

Then Buchanan, drawing on the inventive pseudo-histories of his predecessors, John of Fordoun and Hector Boece, put the myth to immediate political purpose by demonstrating, to his own entire satisfaction, that the Scots had made a habit of deposing any of these kings who proved unsatisfactory. This justified the deposition of Mary Queen of Scots, whom he had come to hate, and was subsequently to prove immensely useful, Trevor-Roper says, to English Whigs in the 17th century.